1. Field of the Invention
The present invention relates to an adaptor assembly for securing a resistive electric heating element to a hot water heating tank and more particularly to a heating tank having an inner glass lining.
In particular, the present invention is concerned with an adaptor which has a hub portion which extends in a hole formed in the side wall of the tank with the hub welded thereto and wherein an adaptor plate is removably retained about a connecting portion of the hub.
2. Description of Prior Art
In the prior art, it was customary to weld the hub to the tank from the interior of the tank. This was a health hazard to the welder because he had to from inside the tank where there was no ventilation. The hub therefore had to be soldered from the outside. However, because the hubs are casted pieces and have an integral connecting flange, it provided difficult to obtain a perfect weld about the hub. After the adaptor was secured to the tank, it was then necessary to subject the tank and the adaptor to temperatures up to 1600.degree. F. in order to adhere a glass lining to the inside of a tank. At these high temperatures, the steel loses carbon and the hub and its flange were considerably weakened. Because the flange is weaken, it often breaks when the resistive element assembly is connected to the flange by bolt fasteners. Because it is very difficult to repair such coupling, often, the tank would be discarded when the adaptor broke. Another disadvantage of using casted adaptors, is that the hub and its flange are often weaken during diecasting and forging as air bubbles form within the metal and form voids and weaken the metal of the flange. The dies for making these adaptors are also very costly. A still further disadvantage of the prior art is the hub of the adaptor is fused in a bore formed in the tank and if the bore is not perfectly round, the fused metal seal developes leaks. Accordingly, known adaptors for connecting resistive heating elements to hot water tanks, particularly glass-lined hot water tanks, have not thus far been adequate in the trades.